Abstract: This paper provides two approaches to calculate tube sheet stress and stress of heat exchange tube corresponding to the effective thickness of the tube sheet of floating head heat exchanger.The first approach is an iterative method for solving the tube sheet stress by using the C curve in GB/T 151 and then obtaining the stress of heat exchange tube;the second approach is to solve the tube sheet stress directly by using the fri curve and mt curve in GB/T 151 and then obtain the stress of heat exchange tube.In engineering practice,these two approaches can be used to calculate the actual stress of the tube sheet and heat exchange tube according to the actual effective thickness of the tube sheet so as to make engineering evaluation on the thickness of the tube sheet.